The present invention relates to venturi type mixing of gas and liquids and more particularly concerns such types of mixing that produce a pulsating discharge of the mixture.
In spas, therapy pools, swimming pools and similar apparatus, jets of water are projected into the body of water contained in the spa, pool or tub to provide a type of hydro-massage, enhanced relaxation and other therapeutic benefits. To increase the action, force and benefit of such jets, the water, before projection, is mixed with air by means of air/water mixers that commonly employ a venturi type action. By this venturi action an increased velocity jet projected into a mixing chamber provides an area of reduced pressure that pulls air into the chamber through a passage that communicates with ambient atmosphere. The air pulled into the chamber mixes with the water and the mixture is discharged through a nozzle into (below the surface of) the body of water contained in the spa or pool tub. Venturi type mixers for spas, therapy pools and the like are typified by those in the U.S. Pat. No. 3,471,091 to Baker; Steimle, U.S. Pat. No. 3,628,529; Jacuzzi, U.S. Pat. No. 3,905,358; Mathis, U.S. Pat. No. 3,890,544; and Mathis, U.S. Pat. No. 3,890,656.
The enhanced massaging and therapeutic actions of pulsating nonaerated water jets are well known and typical devices for providing such water pulsations (without air entrainment) are shown in the U.S. Pat. No. 2,878,066 to Erwin; Donovan, U.S. Pat. No. 1,446,887; Heitzman, U.S. Pat. No. 3,473,736; and Heitzman, U.S. Pat. No. 4,101,075. Pulsed water jets of the prior art have either repetitively diverted the water flow from the desired outlet or repetitively stopped water flow into the water outlet. Prior efforts to provide a pulsed air/water mixer have merely followed principles used in pulsation of nonareated water streams and employed devices to either stop or divert the water flow before it enters the mixing chamber.
Devices that totally obstruct the water flow can cause abrupt pressure increases and noise, imposing severe strains upon the system. Devices attempting to control air flow have generally required external controlling mechanisms and thus become less efficient, more complex, and more costly.
My prior application, Ser. No. 93,754, discloses methods and apparatus for intermittently disturbing venturi action that takes place within the mixing chamber of a venturi type jet so that the resulting discharge of mixed air and water is suitably pulsed. A rotary flow disturbing member, journalled at the nozzle output so as to be driven by the high velocity jet stream is among the more simple of the arrangements disclosed in my prior application. This rotary member intermittently disturbs the stream so as to intermittently disturb the venturi action. Many considerations require that such a flow disturbing member be quite small. Accordingly, its velocity of rotation is high and fixed by physical and flow parameters. A preferred pulsing action occurs at a rate significantly slower than the high rate of rotation of a small rotary disturbing member that is driven by the high velocity jet stream. Adjustable pulsation is often desired. Further, certain provisions in the nature of added elements or configurations of the disturbing member must be provided to ensure start of rotation upon initiation of liquid flow. Such arrangements are not readily adjustable without changing configuration or dimensions of parts.
Accordingly, it is an object of the present invention to provide a venturi type mixer that avoids or eliminates above-mentioned problems and limitations.